Algae as a noun is any of many aquatic photosynthetic organisms, including the seaweeds, whose size ranges from a single cell to giant kelps and whose biochemistry and forms are very diverse, some being eukaryotic. while Algal as an adjective is pertaining to, or like, algae.
Part of speech: noun
Definition: Any of many aquatic photosynthetic organisms, including the seaweeds, whose size ranges from a single cell to giant kelps and whose biochemistry and forms are very diverse, some being eukaryotic.
Part of speech: adjective
Definition: Pertaining to, or like, algae.
We hope you now know whether to use Algae or Algal in your sentence.